China claims most of the energy-rich waters of the South China Sea, through which about $5 trillion in ship-borne trade passes every year. But neighbors Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have claims.

China’s transport ministry held a “completion ceremony”, marking the start of operations at the 55-meter (180-ft) high lighthouse on Subi Reef, where construction began in October, state news agency Xinhua said late on Tuesday.

The U.S. guided missile destroyer USS Lassen sailed within 12 nautical miles of Subi Reef in late October, drawing an angry rebuke from China, which called it “extremely irresponsible”.